The present disclosure relates generally to reduction of surface reflectance in photographic and other images, and more specifically to methods, systems and computer program products for reducing surface reflectance in images using standard camera equipment.
Photography using standard camera equipment can result in undesirable surface reflections (also referred to as surface reflectance) in captured images caused by lighting of the camera or other sources. Such reflections can obscure distinct areas from the image and can interfere with downstream applications.
For example, one application sensitive to such surface reflectance is the screening of skin for skin cancer. Unaided visual inspection of skin features by dermatologists for the detection of skin cancers can have a diagnostic accuracy of around 60%. To improve diagnostic accuracy, dermoscopic imaging was introduced. Dermoscopic imaging, or dermoscopy, is a technique that involves placing a high-resolution magnifying imaging device in contact with the skin. Dermoscopic imaging has been shown to improve recognition performance over unaided visual inspection by up to 50%, resulting in diagnostic accuracies of between 75%-84%.
The generation of suitable photographic images of skin for use in diagnostic dermatological screening applications involves special challenges due to the sometimes very high reflectance of the skin, which can distort the captured image and interfere with diagnostics. Even where lighting is controlled, special procedures and tools are required to remove surface skin reflectance from the captured image in conventional methods. Conventional procedures to remove areas of surface skin reflectance, also referred to as specular reflections, can be burdensome and can require costly equipment. For example, polarization techniques to remove reflectance require use of special filters and, moreover, require controlled lighting conditions that involve a light source of fixed and known direction. Such techniques, for example, cannot be used outdoors where multiple light sources from varying locations exist. In some cases, for example, costly dermascopes can be used. In other conventional methods, where special filters and/or dermascopes are not available, specular reflections can be reduced or eliminated by applying a layer of oil to the skin to act as a medium between a camera lens and the skin, which can be undesirable to a patient.